At least 112 people were killed near Aleppo in Syria on Saturday after a car bomb struck a convoy of buses that had evacuated citizens from two pro-regime towns that had been besieged by the rebels. More than 50 others were injured as the vehicles shattered and caught fire in the suburb of Rashdin in the country’s north-west, CNN reported.

The victim were mainly from the Shia towns of Al-Fu’ah and Kafriya, which backed President Bashar Al-Assad before rebel forces took over them. The Syrian Observatory for Human Rights said a suicide bomber was responsible, and had entered the site claiming he was carrying food. However, the agency said it was unlikely the attack was perpetrated by the regime as the victims were its supporters. No one has claimed responsibility for the bombing yet.

The evacuation was part of the “Four Town deal”, brokered by Qatar and Iran, to aid citizens from besieged towns, according to the BBC. The other two towns are the rebel-held Sunni towns of Madaya and Zabadani. At least 20,000 people are to be moved from these towns, which face daily violence and an acute shortage of food and medical supplies.

More than 3 lakh people have died since the civil war began in Syria in 2011. The war began after Assad’s forces attacked a group of peaceful protestors. Since then, other world powers have become involved, both on Assad’s side as well as with the rebels who oppose him. This was complicated further by the entrance of the Islamic State group in the country’s east in 2014. On April 4, the Assad regime left more than 80 people dead in an alleged chemical attack in the town of Sheikhoun. The United States, which backs the rebels, then launched its own missile attack on a Syrian air base in retaliation, the first time it has directly entered the war.